1. Field of the Invention
The present invention relates to a laser processing apparatus for laser-processing a workpiece such as a semiconductor wafer and a glass substrate.
2. Description of the Related Art
In a fabrication process for electronic parts, a plurality of crossing work lines called streets are formed on the front side of a workpiece such as a semiconductor wafer and a glass substrate to thereby partition a plurality of regions where a plurality of functional devices are respectively formed. The workpiece thus formed with the functional devices is divided along the work lines to thereby produce the individual electronic parts.
Known is a laser processing method such that a laser beam is applied to a workpiece to thereby perform laser processing along the work lines. For example, Japanese Patent Laid-open No. 10-305420 discloses a method of applying a laser beam to a workpiece such as a wafer to thereby form a groove on the workpiece in order to cut the workpiece. Further, JP-T-2004-526335 discloses a method of applying a laser beam along scribe lines (work lines) to thereby cut a semiconductor wafer. In Patent Document 2, two laser light sources (laser oscillating means) are used and the laser beam from each laser light source is branched into a plurality of laser beams to be applied to a circuit board. More specifically, as shown in FIG. 10 of Patent Document 2, two lenses for focusing each laser beam are arranged for each laser light source. With this configuration, laser processing can be performed along a plurality of work lines at a time, thereby improving the processing efficiency.
In performing laser processing along the work lines on the workpiece, a laser applying position and/or the workpiece are/is moved in an indexing direction to thereby move the workpiece relative to the laser applying position, thus stepwise positioning the laser applying position to each work line. Accordingly, in the case of applying the configuration shown in FIG. 10 of Patent Document 2, a laser beam from each of plural laser oscillating means is branched into plural laser beams to be applied to a workpiece. In this case, the amount of movement of the laser applying position and/or the workpiece can be reduced as compared with the case that the laser applying position is single.